Vacuum relay having a pivotally mounted armature



May 27, 1969 J. CAMACHO 3,446,926

VACUUM RELAY HAVING A PIVOTALLY MOUNTED ARMATURE Filed Nov. 22, 1965 INVENTOK JULIAN CAMACHO United States Patent ABSTRACT on THE DISCLOSURE The disclosure relates to avacuum relay comprising an envelope and an electromagnetic actuating assembly supported on the envelope. An armature is pivotally mounted Within the envelope and a mobile contact mounted on the armature and movable therewith to make or break a circuit through a pair of fixed contacts. A resilient bracket is interposed between the envelope and the armature to resiliently retain the armature in operative position withinthe envelope. The armature contains a knifeedge about which the armature may pivot. Shield means are associated with each fixed contact to provide the depositionofvaporized contact material on the portion of the envelope through which each conductive lead extends.

' The invention relates to vacuum relays, and particularly to a relay in 'which an armature is enclosed within a vacuum envelopeand is made responsive to magnetic field generating means outside the envelope.

The conventional manner of supporting an armature within a'vacuum envelope is to provide a hinge plate on which is hinged a spring-pressed armature. The necessity of maintaining close tolerances with this conventional construction is extremely difiicult, and reciprocationof the armature through thousands of operations results in wear with attendant deviation from predetermined toler- Accordingly, it is one of the objects of the invention to provide-a spring-pressed armature for a vacuum relay in which there is no appreciable wear in the cooperating parts, thus precluding deviation from predetermined tolerances so' as to increase the reliability of the relay.

.. It is another object of the invention to provide an armature assembly including a resilient bracket designed to retain the armature in position while imposing resilient bias thereon in a predetermined direction.

3,446,926 Patented May 27, 1969 It is to be understood however that the invention is not limited to the embodiment illustrated and described but may be embodied in various forms within the scope of the appended claims.

Referring to the drawings:

FIG. 1 is a side elevational view, portions of the structure being broken away to show the underlying parts.

FIG. 2 is a vertical cross-sectional view taken in the plane indicated by the line 2-2 in FIG. 1. Portions of the figure are shown in elevation for clarity.

FIG. 3 is a horizontal cross-sectional view taken in the plane indicated by the line 3-3 in FIG. 2.

FIG. 4 is a horizontal cross-sectional view taken in the plane indicated by the line 4-4 in FIG. 2. A portion of the resilient armature retaining bracket is broken away for clarity.

FIG. 5 is a fragmentary view in perspective illustrating the knife edge of the armature which defines the axis about which it is pivoted.

FIG. 6 is a fragmentary sectional view showing the bight for receiving the knife-edge of the armature. The angle through which the armature pivots is indicated by the arrows.

In terms of greater detail, the vacuum relay of the invention comprises a cylindrical dielectric envelope member 2, preferably ceramic, closed at its upper end by end plate 3 brazed to the metallized end-edges thereof, and closed at its lower end by a solenoid assembly designated generally by the numeral 4.

End cap 3 is provided with a suitable tubulation 6 for evacuating the interior of the envelope. The sealed-off tubulation is protected by encapsulating material 7 such as silicon rubber which is in turn covered by a metallic cap 8.

The solenoid assembly includes an outer magnetic housing member 9, within which is supported electromagnetic coil 10, provided with terminals 12 and 13 for connecting the coil to a source of electric power. The coil surrounds a core 14, the inner end of which extends into the envelope 'Itis common practice in the vacuum relay art to utilize a dielectric envelope to support fixed contact members against which a movable contact may impinge to make a circuit through the relay. It has been found that rapid make and break operation of the relay results in the formation of a metal coating on the interior surface of the dielectric members, resulting from vaporization of contact metal. This has the deleterious effect of forming a conductive path over the surfface of the dielectric member between the fixed contacts. Another problem incident to the support of such contacts on the dielectric envelope is the accommodation of varying thermal expansion rates between the dielectric and associated metallic leads supported thereon. Accordingly, it is a still further object of the invention to provide a shield and seal structure associated with each fixed contact which functions to prevent such deposition of vaporized con-tact metal on the dielectric envelope and at the same time functions to seal the metallic lead in the dielectric envelope in a manner eliminating the imposition of destructive stresses on the dielectric member.

The invention possesses other objects and features of advantage some of which with the foregoing will be apparent from the following description and the drawings.

and is surrounded adjacent its inner end by a magnetic plate 16 which seals the inner end of the magnetic housing 9 and cooperates with a radially extending non-magnetic seal flange 17 to seal this end of the relay envelope in a vacuum tight manner. The outer peripheral edge of flange 17 is heliarc welded to the outer peripheral edge of a second superposed seal flange 18 brazed to the associated metallized end of the dielectric member 2.

As indicated best in FIGS 1 and 3, fixed conductive leads 21 and 22 extend through the dielectric envelope portion 2 in coaxial alignment and in a manner which will hereinafter be explained which eliminates the imposition of destructive stresses on the envelope due to differences in the thermal expansion characteristics of the parts. The inner ends of the leads 21 and 22 are spaced apart as shown so as to constitute spaced fixed contacts and are adapted to be bridged by an electrically conductive bridg ing member or mobile contact 23 pivotally mounted on the inner end of a dielectric support rod 24. The lower end of the support rod is engaged by a resilient U-shaped bracket 26 to secure the support rod to a stud 27 brazed to armature 28.

Armature 28 adjacent one of its edges is provided with a knife-edge 29, shown best in FIG. 5. This knife-edge projects into a substantially complementary pocket or bight 31, shown best in FIG. '6, the angle of the knife-edge being somewhat less than the angle of the bight, which is defined on the one side by a tab 32 integral with flange 17, and on the other side by the surface of flange 17 from which the tab 32 is struck. In this manner it will be seen that the armature is permitted to pivot essentially without friction and therefore without appreciable wear on the sharp knife-edge 29 thereof. In order to prevent transverse displacement of the armature, the upstanding 'tab '32 is provided with an aperture 33, as shown best in FIGS. 2 and 4, and the knife-edge of the armature is provided with a lug 34, or portion of the edge not in knifeedge form, adapted to project snugly into the aperture.

To resiliently bias the armature away from the inner end of the core 14, i.e., to cause the armature to pivot upwardly as viewed in FIG. 2 about the knife-edge thereof as a fulcrum, a resilient bracket 36 is provided having a downwardly projecting bifurcated extension 37 engaging a notch 38 formed in' the forward edge of the armature the pocket 31, the extension 37 is engaged with the notched forward edge of the armature, and the lug 42 is engaged in aperture 43. If desired, the lug 42 may be engaged with the aperture '43 prior to engagement of the extension 37 with the forward edge of the armature. The resilient pressure exerted by the resilient bracket 36 retains the armature in assembled position and simultaneously normally biases it away from the inner end of the magnetic core 14. Upon energization of the coil 10, the magnetic field generated thereby attracts the armature down against the resilient force exerted by bracket 36 so that the inner end of the core 14 is abutted by the armature as shown in FIG. 2.

In order to prevent the deposition of vaporized contact metal on the inner surface of the dielectric e'nvelope portion 2, the fixed contact portions of the conductive leads 21 and 22 are surrounded within the envelope by semispherical shields 44 and 45. Each shield is formed with its concavity facing the concavity of the opposing shield, with the adjacent edges of the shields being spaced apart a distance substantially equal to the spacing between the fixed contacts.

The concave shield shells are retained in position by a cylindrical extension 46 brazed to the contact rod as shown. The cylindrical extension is then expanded in diameter so as to provide an expanded cylindrical seal section 47 separated from the coaxially projecting lead by an annular space 48. The expanded diameter seal section is brazed in a vacuum tight manner within appropriate apertures 49 formed in the wall of the dielectric envelope portion 2. The wall thickness of the expanded diameter seal section is such that when brazed or welded to the associated lead the lead and shield form a rigid composite unit. The wall thickness is also gauged to be compatible with the wall thickness of the dielectric envelope assembly the knife-edge of the armature is inserted in so that upon thermal expansion and contraction of the parts the dielectric material dominates the metal seal, thus preserving the integrity of thezseal.

1. A vacuum-relay comprising anenvelope closed at each opposite end, a plurality of {conductive leads extending into the envelopeft'o proyide 'at leastone patter spaced fixed contacts within Ithef'envelopegan electromagnetic actuating assembly supported'on theenvelope and'including anarmature pivotally mounted within the envelope,

a mobile contact mounted orr'the'armature and movable therewith to make ot brealva circuit through at least one pair of fixed contacts, and a resilient bracket" interposed between said envelope and" the'ar'r'natiire' to resiliently retain the armature in operative position vvithiri theenvelope, and shield means asso'ciatd'with cacti-fixed contact to prevent the deposition of vaporizedcontacf'metalon the portion of the envelopethr'oughwhich eachconduc- 'tive lead extends, each said shield means'incmainga semispherical hollowshell having a tubular" extension projecting diametrically therefrom and coaxially arrangedabou't the associated conductive lead, the end bf said tubular extension remote from the semi-spherical "hollow shell being 'united to the envelope in a' vacuu m-tight manner and an intermediate section o f th e'tubular extension being reduced in diameter and united to'the associated conductive lead in a vacuum-tight manner, I

2. The relay according to claim 1, in which said armatureis provided with a knife-edge about which the arrnature may pivot, abutment meansswi-thin. the; envelope forming abight in which the knife-edge 'of the armature is engaged, said resilient bracket retainingthearmature in operative position having one. end thereof anchored within the envelope and the other end engaging thearmature to resiliently bias the knife-edgeof the armature into the bight and bias the armature in a direction away form the electromagnetic actuatingassembly.

References Cited UNITED STATES PATENTS ROBERT s. MACON, Primary Examiner 7 Us. (:1. X3. 17440. 1; 33s -154, 276 

